Collective vibrational states in even erbium nuclei
Abstract
The cross sections for inelastic scattering of 12 MeV deuterons from all the even Er isotopes have been measured at 90° and 125° by means of a magnetic spectrograph. The 2+′ and 4+′ states in the gamma vibrational bands were observed in all nuclei, but only in a few cases the K = 0 β-vibrations were observed. Several octupole vibrational states were identified in each nucleus below an excitation energy of approximately 2.3 MeV. The reduced transition probabilities B(E2) and B(E3) were determined from the observed inelastic cross sections.
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Cited by (122)
Nuclear Data Sheets for A=160
2021, Nuclear Data SheetsThe experimental results published before May 2021 from the various reaction and decay studies leading to nuclides of Z=59 to Z=75, 160Pr, 160Nd, 160Pm, 160Sm, 160Eu, 160Gd, 160Tb, 160Dy, 160Ho, 160Er, 160Tm, 160Yb, 160Lu, 160Hf, 160Ta, 160W, 160Re in the A=160 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. This work is intended to supersede the previous evaluation of the A=160 nuclides by C.W.Reich (2005Re18), which was published in Nuclear Data Sheets 105, 557 (2005).
Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in <sup>168</sup>Dy and <sup>169</sup>Dy
2019, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsThe neutron-rich dysprosium isotopes 168Dy102 and 169Dy103 have been investigated using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity uranium beam in conjunction with isotope separation through the BigRIPS separator at RIBF in RIKEN Nishina Center. For 168Dy, a previously unreported isomer with a half-life of 0.57(7) μs has been identified at an excitation energy of 1378 keV, and its presence affirmed independently using γ-γ-γ coincidence data taken with Gammasphere via two-proton transfer from an enriched 170Er target performed at Argonne National Laboratory. This isomer is assigned based on the measured transition strengths, decay patterns, and the energy systematics for two-quasiparticle states in isotones. The underlying mechanism of two-quasiparticle excitations in the doubly midshell region is discussed in comparison with the deformed QRPA and multi-quasiparticle calculations. In 169Dy, the value for the transition de-exciting the previously unreported isomeric state at 166 keV to the ground state is approximately two orders of magnitude larger than the E2 strength for the corresponding isomeric-decay transition in the isotone 173Yb, suggesting the presence of a significant γ-vibrational admixture with a dominant neutron one-quasiparticle component in the isomeric state.
Nuclear Data Sheets for A=170
2018, Nuclear Data SheetsNuclear structure data pertaining to all nuclei with mass number A=170 have been evaluated, and incorporated into the ENSDF data file. This evaluation supersedes the previous evaluation (Coral M. Baglin), Nuclear Data Sheets 96, 611 (2002), (cutoff date 15 August 2002) and subsequent updates of the ENSDF file for Yb to Dy (cutoff 15 April 2010), Lu (cutoff 8 October 1998), Pt (cutoff 17 February 1999) and Ta, Os (cutoff 7 April 1998). Since the previous evaluation, 170Gd has been observed and the ground state T1/2 measured. New excited states have also been observed in the neutron rich 170Dy. The ground state T1/2 of 170Tb has been determined, however, there are currently still no excited states observed in this nucleus. There remains some uncertainty in the ground state and longer-lived isomer in 170Ir which could warrent further experimental investigation.
Nuclear Data Sheets for A=164
2018, Nuclear Data SheetsExperimental nuclear structure data for the known A=164 isobaric nuclides (Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir) have been evaluated, and presented together with Adopted properties of level energies, and associated γ rays. The decay data for these nuclides have also been evaluated, providing Adopted values of γ and β radiations, and log ft values.
No excited states are known in 164Eu, 164Tb, and 164Ir. Information for 164Gd, 164Re and 164Os is limited due to insufficient experimental data. For radioactive nuclides, decay schemes of 164Sm, 164Gd and 164Re are not known, and those of 164W, 164Tb, 164Lu, 164Hf, 164Ta and 164W are incomplete. The decay schemes of 164Ho and the two activities of 164Tm seem fairly complete. The decay scheme of 164Yb presents a major problem that the Q(ε) value of 887 keV 29 recommended in 2017Wa10 is in disagreement with the population of levels at 928, 952 and 1060 keV in the daughter nucleus. This decay scheme, which so far has been mainly reported in a secondary reference (1982AdZZ) needs further investigation. Also the masses of 164Yb and 164Tm need either new measurements or a re-evaluation to resolve discrepancy of about 220 keV in the Q value of 164Yb decay to 164Tm.
The reactions and decays for which no new experimental information has become available since the 2001 update have undergone revisions to incorporate conversion coefficients from BrIcc code, and evaluated Q values from 2017Wa10, but the essential content of such datasets may have remained the same as in previous evaluations. In this respect the present work greatly benefited from all the previous NDS evaluations (2001Si27,1992Sh07, 1986Sh03,1974Bu30), but at the same time data presented herein supersede all the previous published evaluations.
Nuclear Data Sheets for A=158
2017, Nuclear Data SheetsThe experimental results published before February 2017 from the various reaction and decay studies leading to nuclides 158Nd, 158Pm, 158Sm, 158Eu, 158Gd, 158Tb, 158Dy, 158Ho, 158Er, 158Tm, 158Yb, 158Lu, 158Hf, 158Ta, 158W in the A=158 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. Large sections of the mass chain are almost identical to the ones in the previous 2004He05 NDS publication by R.G. Helmer.
Nuclear data sheets for A = 168
2010, Nuclear Data SheetsNuclear structure data pertaining to all nuclei with mass A=168 (Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt) have been evaluated and incorporated into the ENSDF data file. This evaluation supersedes the previous publication (V.S. Shirley, Nuclear Data Sheets 71, 261 (1994) (literature cutoff date July 1993)) and subsequent ENSDF file revisions for Tb and Dy (C. Baglin, literature cutoff date of 15 June 1999) and Hf (B. Singh, literature cutoff date of 30 April 2001), and includes literature available by 15 June 2010. Since the above evaluations, the first excited states in 168Pt have been identified (1998Ki20, 2009Go16) and α decay from 172Hg has been observed (2009Sa27, 2004Ke06, 1999Se14). New levels in 168Dy have been excited using the 170Er(82Se,84Krγ) reaction (2010So03). (HI,xnγ) studies have significantly expanded our knowledge of level structure in 168Lu (1999Ka17, 2002Ha33), 168Ta (2008QiZZ), 168Yb (1995Fi01), 168Tm (2007CaZW), 168Hf (2009Ya21), 168Os (2001Jo11, 2009Od02) and, for 168Tm, important information has come also from (d,2nγ) and (α,nγ) reactions (1995Si20). Revised decay schemes are available following new studies of 168Hf ε decay (6.7 min) (1997Ba26), 168Lu ε decay (1999Ba65), 168Ta ε decay (2007Mc08) and 172Au α decay (2009Ha42). Significant new information for 168Er is available from (p,t) (2006Bu09), (d,p) and (t,d) (1996Ma50), (γ,γ′) (1996Ma18), (136Xe, Xγ) (2010Dr02), (238U,238) (2003Wu07) and (n,γ) (1998Be20, 1998Be62) reactions, and the availability of γγ coin data (1994Ju02, 1996Gi09) for the (n,γ) E=thermal reaction has resulted in some significant level scheme revisions.
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On leave from the University of Oslo, Norway.